Filezilla server problem

Hi.

I downloaded and installed Filezilla server 0.8.8. I have followed the steps detailed in some websites but my friend still can't connect to the server. He gets a time out error. I dont understand. What could be causing this? I setup a username and password for him and gave him my ip, but it simply doesnt connect. Any ideas?

Edit: I am not behind a router. Also I set one up at his house for me to connect to but I got the same error. I'm thinking I've configured it wrongly but i followed the steps outlined here: http://www.pcmech.com/byos/step/8/

Thanks